Numerous lines of evidence--in particular, studies with lectins--suggest a role for cell surface glycoproteins in the mechanisms of mitogenesis and oncogenic transformation. Analysis of the molecular weight distribution of glycopeptides released from the surfaces of normal and transformed cells have been a frequently used approach to this problem. However, the approach has been limited by the low resolution capability of the gel filtration columns used in the analysis and by the difficulty in relating changes in the molecular weight of glycopeptides to identifiable cellular processes. In preliminary work leading to this proposal procedures have been developed for isolating glycoprotein oligosaccharides and analysing them according to the number and distribution of sialic acid residues. Cell surface sialic acid residues have been shown to play an important role in such diverse processes as tumor invasiveness, survival time of circulating cells, the binding of certain hormones and viruses, and the transport of cations. I propose to use this procedure to compare biosynthetically labelled cell surface and total glycoprotein oligosaccharides from several normal and transformed cell systems. Another approach to this problem will involve selecting variant cell lines (mutants) of normal and transformed cells that lack functional sialyltransferase activities, then comparing the wild-type and variant cell lines with respect to several cellular functions known to be altered by oncogenic transformation, including growth control, adhesiveness, and agglutination by lectins.